Trump and Rove have been feuding in recent works, and the tiff shows no sign of dying down.

On Wednesday morning, Rove appeared on Fox News and downplayed recent poll results that show Trump surging in the GOP 2016 presidential primary.

“The fundamentals matter a lot and Mr. Trump’s fundamentals are not good,” Rove said on “America’s Newsroom,” adding that as the campaign goes on he believes Trump will be exposed as a fundamentally unserious candidate.

Trump has previously bashed Rove for incorrectly predicting the results of the 2012 presidential election, and for what he perceives as ineffective spending by the Rove-linked American Crossroads super PAC, but Wednesday was the first time he specifically called on Fox News to take Rove off the air.

Rove, a longtime aide to George W. Bush, wrote an op-ed in The Wall Street Journal on July 8 under the headline “Trump and Sanders, the Disrupter Brothers.”